Limited landfill capacity and an increase in the environmental awareness and government regulations have spurred efforts for the recycling of post-consumer and post-industrial, synthetic and natural polymeric material. About 6 billion pounds of carpets are produced annually in the United States which start showing up as waste in landfills after about seven years. Currently there are about 8 billion pounds of waste carpets and fabrics that are land filled per year. Waste fabrics and carpet constitute a very serious environmental issue and a very significant financial cost to the manufacturer and consumer.
Typical conventional carpeting includes three primary components: (1) a face yarn that generally consists of nylon 6 or nylon 6,6 fibers with smaller amounts of polyester, polypropylene, acrylics, wool and cotton fibers; (2) a carpet backing that is generally made of polypropylene fibers with a much smaller amount of jute fibers; and (3) an adhesive material that is usually styrene- butadiene rubber and is applied as a latex and cured after application. The adhesive is usually filled with a very high melting inorganic material such as calcium carbonate. These typical carpet constructions are well known in the art and are exemplified in U.S. Pat. No. 4,643,930. Because of the diverse chemical structure of the melt incompatible fiber components of waste carpet, an economical recycling of this material presents a particularly difficult technological challenge.
Waste textiles often consists of blends of fibers having different compositions, yarns containing different fiber types, deniers and colors. This makes reuse and/or separation into individual fiber components difficult. As with waste carpet fibers, melt blending of the synthetic fibers yield melt incompatible materials which have little value.
Previous efforts for disposing of waste fibers by individuals and corporations have relied on burning the waste fibrous materials in massive incinerators, shredding the carpets and/or fabrics and separating the fibers by their density followed by depolymerization to recover the monomers of the polyamides or polyester material, use of supercritical fluids to dissolve the fibers followed by precipitation, and melt extruding the unseparated carpet components into a polyblend composite, which is described in U.S. Pat. No. 5,294,384. The above processes have not been satisfactory from at least one of environmental or economic or technical aspects. Additionally, melt extruded polyblends have particularly weak interfacial adhesion between the incompatible blend components and do not produce a very satisfactory product. Copending and commonly assigned patent application Ser. No. 08/523,257, now U.S. Pat. No. 5,626,939, issued May 6, 1997, coats the shredded waste carpet fibers and fabrics with a structural adhesive and is cured below the melting point of the face yarn.